3D Target Structure Tracking from 2D Projections in Radiotherapy

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Solution Overview

Problem

Conventional methods for tracking planning target volumes (PTVs) and organs at risk (OARs) in radiotherapy are limited by manual template extraction, human error, and inability to accurately estimate motion in low-contrast regions, leading to uncertainty and potential damage to healthy tissues.

Innovation Solution

An end-to-end target structure tracking system using machine learning models to automatically track PTVs and OARs in three-dimensional space, leveraging dual domain conversion of 2D projection data to 3D space, incorporating reconstruction algorithms and recurrent neural networks to predict probability distributions of their locations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional manual template extraction and tracking methods are used, then the process is simple and straightforward, but human error and bias result in large uncertainty margins in PTV and OAR tracking

Engineering Contradiction:
Improvetracking accuracyVSAvoidsystem complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces manual mechanical/template-based tracking methods with an end-to-end deep learning system that automatically extracts features and tracks PTVs and OARs. The neural network models substitute the manual template extraction process, eliminating human error and bias while achieving superior tracking accuracy through automated feature learning from imaging data.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system performs self-service by automatically extracting templates and tracking structures without requiring manual intervention. The deep learning models autonomously learn optimal feature representations and perform tracking, making the system self-sufficient and eliminating the need for operator skill-dependent manual template creation.

Inventive Principle:
Principle #25Self-service

2Measurement precision

If conventional 2D tracking methods are used, then the implementation is straightforward, but the system is limited in locating PTV and OAR in three-dimensional space

Engineering Contradiction:
Improvespatial localization accuracyVSAvoidtracking system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent transitions from 2D projection-based tracking to 3D volumetric tracking by implementing an end-to-end deep learning system that operates in three-dimensional space. The model processes 3D imaging data and outputs 3D localization coordinates for PTVs and OARs, enabling accurate spatial tracking that captures the full anatomical context rather than limited 2D projections.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Measurement precision

If conventional reconstruction algorithms are used, then the processing is faster, but they cannot accurately estimate the motion of PTV and OARs in low-contrast regions

Engineering Contradiction:
Improvemotion estimation accuracyVSAvoidprocessing time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent replaces conventional reconstruction algorithms with deep learning-based motion estimation models. The neural networks automatically learn to estimate PTV and OAR motion from imaging sequences, achieving superior accuracy in low-contrast regions by learning robust feature representations that are insensitive to contrast variations, while maintaining efficient processing speeds through optimized network inference.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Reliability

If manual template extraction is performed, then the user can control the area of interest, but human error and bias create large uncertainty margins in tracking

Engineering Contradiction:
Improvetracking reliabilityVSAvoidoperational simplicity
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The system performs self-service by automatically extracting templates and tracking structures without requiring manual intervention. The deep learning models autonomously learn optimal feature representations and perform tracking, making the system self-sufficient and eliminating the need for operator skill-dependent manual template creation, thereby improving reliability while maintaining ease of operation.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent replaces manual mechanical/template-based tracking methods with an end-to-end deep learning system that automatically extracts features and tracks PTVs and OARs. The neural network models substitute the manual template extraction process, eliminating human error and bias while achieving superior tracking accuracy through automated feature learning from imaging data.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentEP4315246B1Dual domain tracking of target structures
Publication Date: 2025.12.17 SIEMENS HEALTHINEERS INTERNATIONAL AG
  • EP4315246B1 patent drawingFigure 1
  • EP4315246B1 patent drawingFigure 2
  • EP4315246B1 patent drawingFigure 3

AI summary

Embodiments described herein provide for determining a probability distribution of a three- dimensional point in a template feature map matching a three-dimensional point in space. A dual-domain target structure tracking end-to-end system receives projection data in one dimension or two dimensions and a three-dimensional simulation image. The end-to-end system extracts a template feature map from the simulation image using segmentation. The end-to-end system extracts (206) features from the projection data, transforms the features of the projection data into three-dimensional space, and sequences the three-dimensional space to generate a three-dimensional feature map. The end-to-end system compares (210) the template feature map to the generated three-dimensional feature map, determining (212) an instantaneous probability distribution of the template feature map occurring in the three-dimensional feature map.